Cape Town - Mercedes team chief Toto Wolff says "a magic call" in strategy set up Lewis Hamilton's dramatic Spanish Grand Prix victory over Sebastian Vettel.
In Barcelona on Sunday Hamilton slipped from pole to second at the start, recovered and passed Vettel's Ferrari to secure his second win of the season and reduce the German's lead to six points in the title race.
The three-time champion obeyed his team's instructions perfectly as they - led by chief strategist James Vowles - plotted his route to triumph by putting pressure on Vettel in the opening stint and then taking perfect advantage of a Virtual Safety Car (VSC) period.
Vettel pitted early for a new set of soft tyres to end his first stint, but instead of matching that call Mercedes chose to switch to their plan and kept both Hamilton and Valtteri Bottas out for longer stints before Hamilton came in for medium tyres - and leaving the Finn in the lead to block the frustrated Vettel.
The key moment came on lap 34 when Belgian Stoffel Vandoorne of McLaren crashed into Brazilian Felipe Massa's Williams to trigger the VSC.
"That was beautiful for us," said Wolff.
"At that stage we planned to do the opposite to Sebastian -- and then the magic call was the one to pit Hamilton, at a time when it looked like the VSC would end, so Sebastian couldn't react...
"We timed it perfectly -- credit to James and the strategists -- and that pit-stop obviously was much faster than Sebastian's afterwards.
"Then it was down to Lewis to pass him on track which he did on the straight and taking the lead."
That move, which Vettel described as "like a train" passing him, left Hamilton in front for the final stint of 32 laps on soft tyres while Vettel, on mediums, toiled to stay in touch.
"In the end, it was all about balancing on a knife's edge," said Wolff. "You want to have a gap, in the lead, to avoid the undercut, but on the other side we had to make the tyres last 32 laps.
"It was a combination of team work, strategy and Lewis's driving."
Bottas' selfless contribution on a weekend when he was unable to repeat the form that carried him to his maiden F1 win in Russia was also a significant part of their triumph before he retired with an engine failure.
Hamilton says he was left out of breath but relishing the title challenge by the win.
"It's definitely one of the favourites, if not the favourite battle, I'm having," said the three-time champion.
"I'm in a much better position than last year so 2017 is a much better year so far."
"It's great to have a battle - and a fight with another team is so much nicer and more enjoyable because there's no tension within our team.
"At the last race, when Valtteri (Bottas) won, there wasn't an ounce of me that was like 'damn it he won.... But this is how it should be."
Hamilton, who has changed his fitness coaching arrangements and now plans his own schedule between races without a trainer, conceded that he found himself fighting for breath at times.
He had to sit down on the victors' podium during the post-race ceremony, clearly lacking the same level of vim and energy of others around him.
"Man, these cars are so much more physical this year and this is a tough circuit," he explained after the contest at the Circuit de Catalunya where many seasoned observers commented on his condition."